1. Field of the Invention
The present invention relates to state information storage during client side page processing and more particularly to Web data storage for client side page processing.
2. Description of the Related Art
Page processing refers to the receipt, interpretation and rendering of a markup language defined page in a content browser. The most well-known form of a page processing content browser at present is the venerable Web browser in which Web pages are received, processed and rendered. In a conventional Web browser, a markup language page—typically a page defined according to the hypertext markup language (HTML) markup language specification—can be received, interpreted and rendered in a display of a computer. Integral to the HTML processing capabilities of the Web browser is the cookie feature.
The cookie feature provides for short term data storage of state information for a Web page. Cookies have been used for many reasons including session management, personalization and tracking. However, according to the hypertext transfer protocol (HTTP) specification on statement management, a Web browser in respect to the use of cookies need only support a minimal number of cookies. In particular, according to the HTTP specification, a Web browser is expected only to be able to store three-hundred cookies of four kilobytes each, and only twenty cookies per server or domain.
While the cookie feature of HTML can provide a tempting mechanism for data storage in page processing, for many applications—and in particular in light of advances in the acquisition and transfer of digital information such as digital imagery and audio, a client side mechanism of greater capacity is desirable. The HTML version 5 specification addresses this need in defining “Web Storage”. Web Storage picks up where cookies left off. In this regard, Web Storage provides both a simple application programming interface (API) to getter and setter methods for key/value pairs and also a default disk space quota of no less than five megabytes per fully qualified domain name. Within the HTML version 5 specification, Web Storage provides for two object for storing data on a client. The first object is a “localStorage” object that stores data on the client without expiration. The second object is “sessionStorage” which stores data on a client for the duration of a single session.
Consequently, the Web Storage mechanism allows the page developer to define storage for a page of more than just basic user/session info on the client-side. Rather, the Web Storage mechanism permits the storage of user preference settings, localization data, temporary offline storage for batching server writes and much more. Yet further, data stored according to the Web Storage mechanism can be accessed using the familiar JAVASCRIPT™ scripting language, which permits the developer to leverage client-side scripting to do many things that have traditionally involved server-side programming and relational databases.
Despite the advancement in client side storage offered by the Web Storage mechanism in HTML version 5, the Web Storage mechanism is not without fault. First, as clients become more robust and more application code executes within the content browser, the need to cache client side generated content increases. Due to the limitations in the size of the cache, the ability to cache large amounts of client generated content is not available. Secondly, as the number of devices increase per user, there is a increased value in having the ability to share data between these devices which is not possible with the Web Storage mechanism in HTML version 5. Of course, an application server could be leveraged for storing shared data. However, the use of an application sever to store shared data conflicts with a primary motivation for the Web Storage mechanism—to offload storage of user data from the application server—particularly when running applications offline.